Prospective study of a 'popping' sound during percutaneous radiofrequency ablation for hepatocellular carcinoma.

PURPOSE: To prospectively evaluate the occurrence of a 'popping' sound during radiofrequency (RF) ablation for hepatocellular carcinoma (HCC) and its association with early tumor progression and patient survival.

MATERIALS AND METHODS: Seventy-six patients with 100 tumors underwent RF ablation by using an internally cooled electrode. A popping sound was defined as an audible sound or tactile vibration detected by the operator during RF ablation. Follow-up ranged from 6 to 38 months (mean, 19 months) and included 3-6 month ultrasonography, serum alpha-fetoprotein measurements, and computed tomography or magnetic resonance imaging. Early local and distant intrahepatic tumor progression within 12 months and survival were analyzed.

RESULTS: A popping sound occurred during 58 of the 100 (58%) tumor ablations. Primary technique effectiveness was achieved in 97 of the 100 (97%) tumors. Major complications occurred in 2 of the 76 patients (2.6%). The cumulative rate of early local tumor progression was 20.8%. At multivariate analysis, early local tumor progression was associated with tumor size larger than 3 cm (odds ratio [OR] = 4.08, P = .012) and inversely associated with a popping sound (OR = 0.267, P = .026). The cumulative rate of early distant intrahepatic tumor progression was 21.4%, and the cumulative survival of the whole cohort at 6, 12, 18, and 24 months was 98.7%, 96%, 92.7%, and 83.6%, respectively. A popping sound was not significantly associated with either early distant intrahepatic tumor progression (P = .341) or patient survival (P = .975).

CONCLUSIONS: A popping sound during RF ablation is not associated with an increased risk of early tumor progression or poorer patient survival.